In the cutting of metal rod materials, and in particular, toughened surgical steel, superior accuracy is required given that the rod being cut is used inside a patient's body. In the past, bolt cutting devices have been used by surgeons having compound levers and pivoted jaws. The problems encountered with such bolt cutting devices, however, is that the cut ends of rods were often left rough or having a wedge-shaped tip due to the extreme compression of metal during the cutting operation. Bolt cutters also prove to be difficult to use in the operating room due to the possibility that work pieces have been known to be propelled in unpredictable directions during the cutting operation, causing concern for operating personnel, as well as patients. In particular, when a rod is cut in this manner while a portion is in the patient, the force from such a compressed type cut will also be transmitted to the rod section in the patient causing some fracture of the implant placement in the bone. Moreover, given the extreme toughness of surgical metal rods, conventional bolt cutters are often difficult to operate manually and require significant strength of the operator. Numerous rod and bolt cutters have been developed having various designs and that are capable of providing a satisfactory cutting edge of a hardened surgical steel rod. For example, U.S. Pat. No. 5,261,303 to Strippgen describes a rod cutter that operates by a shearing action with applied rotatory torque, shearing surgical metal rods with excellent smoothness on the cut end. A disadvantage with this rod cutter device, however, is that during the final rotary motion of the cutting operation the operator's hand would often come into contact with a table top surface upon which the rod cutter was placed. Moreover, the design incorporates a pivotable handle that folds toward the cutting assembly in a manner wherein the hand grip area of the handle (where rod cutting force is applied) is narrow, having substantially no width on the inner side of the fold of the handle.
In another known rod cutter, having a pivotable handle, the handle is deformed with an offset to accommodate a wider hand grip when folded. However, the offset handle position is uncomfortable for a user and is necessarily outside the plane of rotary motion of the handle when used for cutting a rod. Further, such a pivotable handle has been the cause of a pinched finger or hand while setting up for use.
It would be desirable to have a compact, manually operated surgical rod cutting device that has an extensible handle for increased rod cutting leverage without any pivotal action to extend the handle. Further, it would be desirable to have the handle entirely within the plane of rotary motion during the rod cutting process. Additionally, it would also be desirable to have the handle configured in such a way that there is less potential for damage to an operator's hand when performing the cutting operation. Moreover, a rod cutter for surgical steel rods should be of a size that permits ready sterilization of the unit as a whole, as well as individual parts of the unit.